The present invention relates to a rotary mechanism wherein a shaft having at least one free end and a housing rotatably fitted thereover are rotated relatively with respect to each other through contactless or axial bearings.
Employed as rotary head cylinder assemblies in video tape recording systems (to be referred to as "VTR" for brevity in this specification) are rotary mechanisms wherein a rotating member such as an upper cylinder is rotatably supported at one free end of a shaft, the other end of which is clamped, in point or line contact relationship with each other or wherein a rotating member is mounted on a shaft through anti-friction bearings such as ball or roller bearings. However such supporting or bearing systems as described above have their inherent problems. When the rotating member is supported at one end of the shaft in point contact relationship therewith, rapid wear of the bearing surfaces results, so that the relative position between the rotating member and the shaft changes. When the rotating member is supported at one end of the shaft in line contact relationship therewith, a high starting torque is needed because of a high resistance between the bearing surfaces. When the rotating member is supported on the shaft through the anti-friction bearings, the axial position of the rotating member relative to the shaft cannot be maintained accurately as will be described in more detail hereinafter.